The science behind permanent hair colors is very fascinating and it raises a lot of questions from stylists and clients alike, especially around some of the ingredients they're made of, like ammonia.
Is ammonia a safe ingredient? Why is it used in permanent colors? Is an "ammonia-free color" damaging the hair less? Here's the science behind the marketing.
First of all, let's examine what ammonia is. Ammonia is a natural ingredient, naturally present in the human body as a byproduct of biological processes. It is also present in many food products we consume every day: If you like French cheese, you might be familiar with that typical smell associated with it. Did you know that part of that smell is ammonia and similar molecules? Also, baker's ammonia is widely used as a leavening agent for the production of cookies.
Why is ammonia used in hair colors? Because it's an alkalizing agent, which means it's able to raise the pH of a color to alkaline levels. This is oftentimes crucial to ensure that the hair outer layer swells so that active ingredients (like hair dyes) can penetrate it, and to promote the chemical reactions that ensure up to 100 percent gray coverage, creation of vivid tones and hair lightening.
Some people believe that a color without ammonia is better for the hair. Science tells us that this is not necessarily true: From a chemical point of view, ammonia is a very small molecule, and that's good because it makes it very effective, as it acts fast and is easy to wash off. But the small size of the molecule also makes it very light and easy to evaporate and reach our nose receptors, hence the typical smell.
"Ammonia-free" products typically replace ammonia with an alternative alkalizer, MEA, which is a less effective derivative of ammonia: Its molecule is made of ammonia linked to an “ethanol" group, which makes the molecule become bigger and heavier. Consequently MEA doesn't evaporate, which means you don't smell it, but it's also bulkier and less efficient and needs to be used in higher concentrations to achieve comparable permanent color performance.
In conclusion, science tells us that ammonia is a natural molecule that we can easily find around and inside us, and it's a safe and efficient ingredient for permanent hair colors.